Wall covering systems for interior and exterior of building walls using cement type coatings are popular in the building industry because of the relatively inexpensive form of construction and covering of large expanse of walls. Such coverings may be applied to refurbish existing building exteriors and interiors, or applied to new building construction.
Horbach, U.S. Pat. No. 3,389,518, provides a continuous finish for a building exterior. A form of cellular insulation is adhesively applied to building exterior. A continuous layer of cementitious material is applied over the cellular insulation and reinforcement in the form of glass fibre fabric or reinforcing fibres is incorporated in the cementitious material. A finish coat of synthetic materials, such as propionic acid ester or other binder materials, is applied to the cementitious layer. The finish coat may include a mineral aggregate for decorative purposes. The purpose of this structure is to prevent crack propagation in the building wall being transmitted to the newly completed surface, thereby preventing crack formation in the new finish. Horbach does not recommend the use of steel plates on the face of the insulation because of heat conductivity and their exceptional weight. The steel plates would have to be firmly secured to the building exterior and cannot compensate for temperature variations that can form cracks in the surface of the finish material applied to the insulation.
Heck, U.S. Pat. No. 4,318,258, discloses improvements in the use of Styrofoam (trademark) panels which are affixed to building walls. The insulation panelling has a special grooving arrangement to compensate for expansion and contraction in the panels. A cement layer is applied over top of the foam layers. The plaster or mortar may contain synthetic resins, such as methyl cellulose and polyvinyl propionate. Other suitable plastic resins include homopolymers, copolymers of acrylic acid and methacrylic acid, e.g. styrol acrylates and vinyl acetates. The foam slabs as grooved are glued to the building exterior in a manner similar to that discussed in Horbach, U.S. Pat. No. 3,389,518.
A comparable system involving the use of Styrofoam panels is disclosed in Canadian patent No. 1,148,324. The Styrofoam panels having grooves on the interior and the exterior are applied to a building wall using fasteners. The base coat of plaster or mortar is applied over the Styrofoam panels where the cementitious material is received in the outer grooves of the Styrofoam panels to ensure that the hardened base coat material is firmly affixed to the Styrofoam material. When the Styrofoam material moves due to expansion and contraction caused by temperature extremes, cracking in the base coat can occur.
Burrows, U.S. Pat. No. 4,044,520, discloses a building panel system which is a modular unit glued to the building exterior. Each building panel as preformed consists of a foamed resin insulation layer over which a base coat and finish coat are applied. A polymer fortified concrete base coat may be used. Polymer fortification of the cement may be provided by an acrylic polymer together with a defoaming agent. The outer facing layer may be of a synthetic binder material, such as an acrylic polymer optionally used in combination with concrete. Aggregate may be added to the binder material to enhance the appearance of the building panels. These individual preformed panels have edge portions formed in a manner so that, when the panels are glued to the building exterior, the edges overlap in a mating manner to provide a modular type exterior finish for the building. The unfortunate problem with this system is that, if the building exterior is of uneven plane, then the panels as applied to the building exterior also take on the uneven plane of the building.
Rubenstein, U.S. Pat. No. 2,850,890, discloses a precast building block having applied to an exterior surface thereof a polyester resin impregnated with fiberglass or like types of fibre reinforcing materials. Such fibres may be provided in the form of woven or unwoven mats, fibrous stranded materials or rope. The fibrous material is impregnated with polyester resins so as to adhere the fibrous material to the face of a concrete block and to essentially cover the thickness of the fibrous material. A finishing layer may be adhered to the layer of fibrous materials. The preferred type of fibrous material, as disclosed in this patent, is of the "Fiberglas" (trademark) type which would be in the form of a mat. This type of fibrous material is fairly dense and hence does not allow the resins to fully impregnate the layer of fibrous material resulting in poor adhesion of the fibrous material to the cement block. After the finish coat is applied to the fibrous material, it is possible over time that the polyester resins release their holding power on the cement blocks, thereby causing the surface finish to blister and fall away from the cement blocks.
Another form of wall cladding system, which involves the use of a form of fibrous insulation, is disclosed in U.S. Pat. No. 4,606,168. In that system, a plurality of insulation batts of fibrous material are affixed to a building wall by fasteners having plate portions with apertures extending therethrough. When the cementitious layer is applied over the insulation and forced through the apertures in the plates of the fasteners, a suspension of the exterior hardened cementitious layer is achieved by way of the fasteners. This accommodates expansion and contraction in the materials without inducing cracking in the exterior surface.